Magnetic materials have been used in functional devices for decades, such as recording devices including hard disk drives (HDDs), magnetoresistive random-access memory (MRAM), bubble and thin-film data storage, sensor and domain shift register devices. Most of these traditional functional devices are based on the control of magnetic domains. For example, recording media use single magnetic domain states with two opposite magnetization directions to represent the information bits 0 and 1. Material morphology, geometry and intrinsic parameters influence the specific magnetic domain formation and shape, and hence, do directly or indirectly affect the relevant functionalities based on magnetic domains. Magnetic domain walls have been moved and transformed by a magnetic field or a spin-polarized current in planar magnetic wires and rods resulting in new concepts for magnetic memory, storage and logic devices.
In the document by Fert, A., Cros, V. & Sampaio, J. Skyrmions on the track. Nature Nanotechnology 8, 152 (2013), magnetic skyrmions are described which are nanoscale spin configurations that hold promise as information carriers in ultradense memory and logic devices owing to the extremely low spin-polarized currents needed to move them. Magnetic skyrmions are chiral spin structures with a whirling configuration. As their structure cannot be continuously deformed to a ferromagnetic or other magnetic state, skyrmions are topologically protected and relatively stable structures, in comparison with, for example, magnetic vortices or bubbles. To figure out how to stabilize skyrmions on tubular nanosized magnetic wires is still a big challenge.